WASHINGTON
— The US Supreme Court has agreed to decide a dispute over whether the Environmental Protection Agency has the power to regulate emissions of carbon dioxide and other greenhouse gases said to be contributing to global warming.

The high court listed the case, Commonwealth of Massachusetts v. US Environmental Protection Agency, among five cases it agreed on Monday to decide in its next term that begins in October.

The action sets the stage for what could be a major ruling on the scope of federal power to protect the environment. At issue is a 1999 effort to force the EPA to attack global warming with its regulatory powers.

The agency balked, saying the Clean Air Act did not grant it authorization to undertake a regulatory program with such potentially massive implications for the US economy and foreign policy. In addition, the EPA said that even if the Clean Air Act did authorize action on the issue, the agency nonetheless has the discretion to await the conclusion of ongoing scientific studies before moving forward.

A divided appeals court panel in Washington, D.C., upheld the agency's position in a ruling issued last July.

The petition urging EPA action was filed by attorneys general from 12 states, and lawyers for three cities, a US territory, and various environmental groups.

"The question of whether and to what extent this nation should be addressing global climate change is one of the most important public health and welfare issues of the twenty-first century, with extraordinary implications for present and future generations of Americans," writes James Milkey, an assistant Massachusetts attorney general, in his appeal asking the Supreme Court to take up the case. "We believe that the science is clear that EPA should act."

The Bush administration disagrees. Administration lawyers told the high court that the attorneys general and others lack standing to bring the legal action. They further argue that the Clean Air Act does not empower the EPA to regulate greenhouse gases, and that it was a reasonable exercise of agency discretion for the EPA to decline to take up the issue prior to additional scientific study.

"EPA reasonably concluded that the term 'air pollution agent' as used in the regulatory provisions (of the Clean Air Act) cannot be interpreted to encompass global climate change," writes US Solicitor General Paul Clement, in his brief urging the high court to reject the case.

At the center of the dispute is the question of whether government action on global warming requires additional and specific legislation from Congress, or whether existing laws and the EPA's own regulatory power are enough to address the controversial issue.

The 12 attorneys general and environmental groups say Congress has already created a government structure capable of dealing with the problem. They say the agency is attempting to rewrite the law by administrative fiat, replacing Congress's policy choices with its own.

"EPA cannot ignore a congressional mandate that it 'shall' regulate dangerous substances simply because it disagrees that such regulation would be a good idea," Mr. Milkey writes.

Solicitor General Clement says the Clean Air Act is aimed at regulating substances that make clean air dirty, as opposed to greenhouse gases that make cool air warmer. In the government's view, although a warmer atmosphere may pose environmental threats, it is not the kind of "pollution" Congress sought to address in the Clean Air Act.

Critics of the legal action against the EPA say it is an attempt to require the agency to enforce provisions of the Kyoto Protocol to prevent global warming, even though the Senate has declined to ratify the United Nations treaty.

Indeed, several industries lined up with the EPA, and filed supporting legal briefs.

"Our position is that the Clean Air Act does not authorize the regulation of CO2 by the EPA," says Gloria Bergquist, vice president of the Alliance of Automobile Manufacturers, a Washington trade group that represents global automakers in the US. "We have supported voluntary efforts to reduce carbon dioxide. It's our position that while the global debate continues, it's only prudent to reduce CO2 from our facilities and our products."

Environmental groups feel differently. "The Bush Administration has continually tried to say that it's not their job to fight global warming. In fact, they have both the legal and moral responsibility to tackle global warming pollution," said David Bookbinder, senior attorney for the Sierra Club in a statement Monday.